In heterogeneous networks where small cells are placed within homogeneous macro coverage, user equipment (UE) will experience significantly higher interference levels compared to a homogeneous macro network scenario. The number of unknown parameters associated with the interfering transmissions makes accurate interference cancellation/suppression challenging and often inaccurate. In addition, interference cancellation/suppression may present a challenge in homogeneous macro networks where UEs are located close to the cell edge.
To help the UE in mitigating the interference, a network assisted interference cancellation (NAICS) study was introduced in Third Generation Partnership Project (3GPP) standardization. NAICS aims at improving inter-cell interference mitigation by providing knowledge about interfering transmissions with possible network coordination to the victim UE. The potential gains of advanced UE receivers with network assistance were identified as part of the study. By increasing the degree of knowledge about interfering transmissions with possible coordination in the network, enhancements to intra-cell and inter-cell interference mitigation at the receiver side may be achieved.
A conventional receiver, which does not receive scheduling information about interfering cells, uses the information transmitted on the control and broadcast channels (PBCH) and other parameters provided by the searcher, and higher layers to obtain a preliminary interference classification. Unfortunately, this information is often not sufficient to correctly assist the receiver in generating accurate estimates of the physical layer parameters. As a consequence, the conventional receiver is designed in a conservative way and for the worst case scenario thus compromising performance in many configurations.